JP2009044536A - Color image having predetermined image embedded in original image, color image forming method and device therefor, and image processing method and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To embed an image that a person can recognize in an original image in an easy manner. <P>SOLUTION: Two kinds of output profiles (color separation conditions) of the same color reproduction and different ink combinations are used and while a first output profile is allocated to one area of the original image Ia, a second output profile is allocated to the other area of the original image Ia. Namely, the output profiles are changed according to pixel positions in the image to perform image processing, thereby embedding the buried image Ii in the original image Ia. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides a color image (a color image in which a predetermined image is embedded in an original image) in which a color is determined by a total amount of color material formed on a base material such as a sheet and overlapping color materials for each pixel, and the color The present invention relates to an image forming method and apparatus, and an image processing method and apparatus.

  Techniques for forming an image in which an original image is embedded with a watermark or the like have been proposed (Patent Documents 1 and 2).

  Patent Document 1 discloses an information embedding device and an embedding information restoring device that can embed a large amount of watermark information in a natural image in an invisible state and can restore the watermark information even if there is no position information in which the watermark information is embedded. Is described.

  However, with this technique, a human cannot visually recognize a watermark, that is, an embedded image.

  Patent Document 2 discloses a printing technique capable of recognizing a color latent image having light and shade gradations when observed obliquely.

  However, this technique requires a dedicated device for intaglio printing, embossing and scoring to form a color image with a color image line and a relief pattern line.

  On the other hand, according to the present invention, it is possible to embed an embedded image that can be recognized by a human in an original image by a relatively easy method.

  Conventionally, in an electrophotographic printer that uses toner as a color material, an ink jet printer that uses ink as a color material, or a color image forming apparatus such as a printing machine, the color material is stacked on a substrate such as a sheet. A color image is formed.

  As an image forming body, an image forming apparatus, and a receiving layer transfer material on which unevenness is formed (a relief is formed) to which the present invention can be applied, a dye receiving layer on a relief forming layer surface having a white reflection function is on demand. Receiving layer transfer material capable of obtaining a high design image having both white diffused light from the relief forming layer or white light in a specific angle range and a color material image by printing and forming an image by a printing method , A transfer sheet, a colorant receiving sheet with a relief layer, and an image formed product using them (Patent Document 3).

  The present invention can also be applied to a relief image forming apparatus using ink that is useful in an ink jet system in which ink is ejected by generating bubbles with an electric heat exchanger (Patent Document 4).

  Furthermore, the first message image area printed with the optically changing ink on the surface of the base material, and the first message image area printed on the surface of the first message image area with the swelled ink. The present invention can also be applied to an image forming body having a configured second message image area (Patent Document 5).

JP 2000-138815 A JP 2000-313160 A JP 2006-218847 A JP-A-8-60054 JP 2006-123355 A

  As described above, an object of the present invention is to provide a color image in which an image is embedded in an original image and a human can recognize the embedded image by a relatively easy method.

  Another object of the present invention is to provide a color image forming method and apparatus, an image processing method and apparatus capable of embedding an image recognizable by humans in an original image by a relatively easy method. .

  A color image in which a predetermined image is embedded in an original image according to the present invention is a color image formed on a base material, and the color is determined by a total amount of color material obtained by overlapping color materials for each pixel. The embedded image includes an embedded image in which a predetermined image is embedded, and the embedded image has the same color reproduction as the original image at each pixel position of the embedded image, and the original image The total color material amount is different from the total color material amount.

  According to the present invention, it is possible to embed an image (embedded image) in the original image by utilizing the difference in film thickness due to the total amount of color material while maintaining the color reproduction of the original image itself. Since the film thickness differs between the original image and the embedded image, a human can recognize the embedded image.

  The color image forming method according to the present invention is a color image forming method for forming a color image on a substrate by determining a color based on a total amount of color materials obtained by overlapping color materials for each pixel, wherein the color image is an original image. A plurality of output values for reproducing each pixel of the original image with the same color of a different total amount of color material when the color image is created, including an embedded image in which a predetermined image is embedded; The method includes a step of preparing an output profile, and a step of assigning different output profiles in the plurality of output profiles to the original image and the embedded image, respectively, and reproducing colors.

  The color image forming apparatus according to the present invention is a color image forming apparatus that forms a color image on a substrate by determining a color based on a total amount of color materials obtained by overlapping color materials for each pixel, and the color image is an original image. Means for preparing a plurality of output profiles for outputting a color separation value for reproducing each pixel of the original image with the same color of a different total color material, including an embedded image in which a predetermined image is embedded; Means for assigning different output profiles in the plurality of output profiles to the original image and the embedded image, respectively, and reproducing the color.

  According to the color image forming method and apparatus of the present invention, the original image and the embedded image are selectively used with the same color reproduction and a profile that uses different total color material amounts. An embedded image (relief image) can be formed by utilizing its own color reproduction. Since the total amount of color material differs between the original image and the embedded image, a human can recognize the embedded image.

  The image processing method according to the present invention is applied to an image forming apparatus that uses, on four or more color materials, a color image including an embedded image in which a predetermined image is embedded in an original image. In the image processing method, a combination of a plurality of color materials that reproduces the same color as the color to be reproduced for the pixels of the original image and has a different total color material amount is acquired, and corresponds to the pixel position of the original image According to a pixel value of a pixel of the embedded image, a combination of color materials for forming the embedded image is obtained from the combination of the plurality of color materials.

  The image processing apparatus according to the present invention is an image processing apparatus for an image forming apparatus that uses a color material of four or more colors to form a color image including an embedded image in which a predetermined image is embedded in an original image on a substrate. In the apparatus, a unit that reproduces the same color as the color to be reproduced with respect to the pixels of the original image and that obtains a combination of a plurality of color materials having different total color material amounts, and corresponds to the pixel position of the original image Means for obtaining a combination of color materials for forming the embedded image from a combination of the plurality of color materials according to a pixel value of a pixel of the embedded image.

  According to the image processing method and the apparatus of the present invention, a color image that can be recognized by a human can be embedded in an original image by a color image forming apparatus that performs color reproduction with four or more colors by a relatively easy technique.

  All the above-described inventions can be applied to electrophotographic printers that use toner as a color material, inkjet printers that use ink as a color material, or color image forming apparatuses such as printers, post-processing and post-processing. Is unnecessary.

  According to the present invention, it is possible to provide a color image in which an image is embedded in an original image and a human can recognize the embedded image by a relatively easy method.

  Further, according to the present invention, an image that can be recognized by a human can be embedded in an original image by a relatively easy method.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of an image reproduction system 10 to which a color image forming method, a color image forming apparatus, an image processing method, and an image processing apparatus according to an embodiment of the present invention are applied.

An image reproduction system 10 according to this embodiment basically includes a personal computer 12, a color scanner (image input device, image input device) 14 connected to the personal computer 12, and a color printer (image forming device, image). (Output device, image output device) 16 and a colorimeter 20 that outputs a device independent value of the read image, here Lab (L ^* a ^* b ^* ).

  The color scanner 14 reads a color image from an original image (color original) Ia such as a color reversal film, and the original image data O (x, y) {collection of pixel values at coordinates (x, y) as color image data. } Is sent to the personal computer 12 as device values (device-dependent values) RGB (red, green, blue).

  Examples of the image input device include a color camera and a digital camera. The original image data O (x, y) composed of device values RGB can also be acquired through a recording medium such as a CDROM or an electric communication line such as the Internet.

  The personal computer 12 is connected to an input device 30 such as a CPU 22, a memory 24, a color monitor 28, and a keyboard mouse through a bus, an interface 32 that receives device values RGB from the color scanner 14, and a color printer 16 for each pixel. An interface 34 for sending device values CMYK (cyan, magenta, yellow, black) as pixel values and an interface 36 for receiving device independent values Lab as colorimetric values from the colorimeter 20 are connected.

  The memory 24 includes a DRAM (main memory), a flash memory (rewritable non-volatile memory), and the like. The CPU 22 executes programs stored in the memory 24 based on various inputs, thereby realizing various function implementation means. Function as. In this embodiment, the CPU 22 converts the device value RGB or device value CMYK of the color scanner 14 into a device independent value Lab or the like (input profile: A2B), and converts the device independent value Lab into the device value CMYK of the color printer 16. Means (output profile: B2A), means for preparing a plurality of output profiles (B2A), means for assigning an output profile (B2A) to reproduce colors, and a plurality of inks (color materials) having different total ink amounts (total color material amounts) It functions as a means for obtaining a combination of the above, a means for obtaining a combination of inks (color materials), and other various calculation means.

  Here, “profile” will be generally described. “Profile” refers to a conversion function of two different color spaces. An ICC profile based on specifications defined by ICC (International Color Consortium) is widely used.

  An “input profile” is a profile of an input device (scanner, digital camera, etc.). An “output profile” is a profile of an output device (printer, printing, etc.).

Usually, the input and output profiles describe the relationship between a device-dependent color space and a device-independent color space. Thus, the input color space signal and the output color space signal can be converted through the common device independent color space. In ICC, the device independent color space is called PCS (Profile Connection Space). The following is an example of a color space defined by the ICC.
Device dependent color space: RGB, CMYK, 5CLR, 6CLR, 7CLR
Device independent color space: XYZ, Lab, Luv, YCbr, Yxy

  In the ICC, especially when color space conversion is performed using a table (LUT), the device dependent color space is A, the device independent color space is B, and the conversion from the device dependent color space to the device independent color space is A2B, device independent. The conversion from the color space to the device-dependent color space is named B2A (the name for the color space conversion is not related to input / output). Note that the color space conversion can be performed by matrix calculation, but the conversion in this case is not A2B or B2A.

  If Lab is used as the device-independent color space, and the device-dependent color space is RGB color space in the input profile, RGB → Lab conversion is A2B, Lab → RGB conversion is B2A, and the device-dependent color space is in the output profile. In the CMYK color space, CMYK → Lab conversion is A2B, and Lab → CMYK conversion is B2A.

  When converting “input color space → PCS → output color space” using an ICC profile in which conversion characteristics are described by a table, the former conversion uses the input profile A2B, and the latter conversion uses the output profile B2A. Will be done. Also, if defined, reverse conversion “output color space → PCS → input color space” is possible. In this case, the former stage conversion is performed using the output profile A2B, and the latter stage conversion is performed using the input profile B2A. The above description is the description of “profile”. A procedure for creating an input profile and an output profile required in this embodiment will be described later.

  In FIG. 1, the color printer 16 provides a hard copy in which a color image Ib in which an embedded image Ii (character “A” in FIG. 1) is embedded in an original image Ia is formed on a base material 40 such as a sheet. HC is output.

  FIG. 2 is a functional block diagram showing a data flow in normal image processing of the image reproduction system 10 when the embedded image Ii is not embedded.

  In FIG. 2, the original image data O (x, y) supplied from the color scanner 14 is composed of a set of pixels at coordinates (x, y).

  The device value RGB of the original image data O (x, y) includes an input profile (input color conversion characteristic: A2B) 50 for converting the device value RGB for each pixel into a device independent value Lab such as a colorimetric value in a common color space. The converted device independent value Lab is converted into the device value CMYK which is a color separation value through an output profile (output color conversion characteristic: B2A) 52 which converts the device independent value Lab into a device value CMYK for supplying to the color printer 16. A set of pixels based on the device value CMYK is processed image data P (x, y).

  In this embodiment, the output profile (B2A) 52 targets a color image using inks of four or more colors of CMYK as color materials. In addition to CMYK, color images including light cyan, light magenta, and special colors can also be targeted.

Here, the input profile (A2B) 50 is a color conversion that converts the color space of the original image data O (x, y) into common color space data such as a device independent value Lab (L ^* a ^* b ^* ) chromaticity value. The output profile (B2A) 52 is a color conversion characteristic from the common color space to the color space of the color printer 16 such as the device value CMYK.

  To create the input profile 50 (A2B), as shown in FIG. 1, in place of the original image Ia, a number of color patches formed on a color chart Ie appropriately designed with respect to hue, saturation, and brightness. Ig is read by the color scanner 14 to obtain a device value RGB for each color patch Ig, and the color patch Ig is measured by the colorimeter 20 to obtain a device independent value Lab. 24.

  The CPU 22 creates an input profile (A2B) 50 by associating the relationship between the device value RGB thus obtained and the device independent value Lab, and stores it in the memory 24 as the input profile (A2B) 50.

  In this case, since the device independent value Lab and the device value RGB are both three-dimensional and have a one-to-one relationship, the interpolation calculation can be applied to both the common color space and the device color space. An input profile (B2A) is obtained by performing interpolation on the common color space, and an input profile (A2B) 50 is obtained by performing interpolation on the device color space.

  The memory 24 also includes an output profile (B2A) 52 for converting the device independent value Lab for the color printer 16 into the device value CMYK, and conversely, the color printer 16 for converting the device value CMYK into the device independent value Lab. The output profile (A2B) 54 is stored. Here, the output profile (A2B) 54 is referred to as an output forward profile (A2B) 54.

  In creating the output profile (B2A) 52 and the output forward profile (A2B) 54, the CPU 22 prepares color chart data appropriately set in the device color space of the color printer 16. In the case of printing four colors, the data of the CMYK halftone multiplication chart is used.

  Based on the color chart data, each patch Ip of the color chart Id output onto the substrate 40 by the color printer 16 is measured by the colorimeter 20 to obtain a device independent value Lab.

  The set value of each patch Ip of the color chart Id at the time of output profile creation can be taken on the grid points in the output color space. For example, in the case of CMYK 4 color 11 grids, the total grid point number is 11 (C) × 11. (M) × 11 (Y) × 11 (K) = 14641 points, and it is not realistic to take data by charting all points. Actually, a color chart Id is composed of several hundred patches, an interpolation operation is performed on a set of the color chart Id and the colorimetric data of each patch Ip, and an output forward profile (A2B) for all grid points in the output color space. ) 54 is obtained.

  Since each variable of the device color space CMYK is independent, conversion from a three-dimensional device-independent space to a four-dimensional device color space is not uniquely determined. By giving K as a condition to the device independent value Lab, the correspondence relationship from the device independent value Lab to the device value CMY is obtained. An interpolation calculation is performed on these data sets to obtain an output profile (B2A) 52 for all grid points in the device color space.

  In this way, the output forward profile (A2B) 54 for the color printer 16 (conversion characteristics / table from the device value CMYK to the device independent value Lab of the color printer 16) and the output for the color printer 16 in the opposite direction. A profile (B2A) 52 (conversion characteristics / table from device independent value Lab to device value CMYK) can be created.

  By the way, when color reproduction is performed using four or more colors of ink, there is generally not one combination of inks that reproduces a specific color. For example, under certain printing conditions, the first combination [C: 55%, M: 100%, Y: 12%, K: 0%] and the second combination [C: 48%, M: 95%, Y : 0%, K: 12%] are the same color (the same color reproduction).

  Therefore, the output profile (B2A) 52 is a plurality of output profiles having different K values that reproduce the same color, for example, as shown in FIG. 1, the output profile 52A (B2A-A) and the output profile 52B (B2A-B). Can be created as

  Since each ink of the device value CMYK has a small film thickness, when the ink is printed on the base material 40 such as paper in order, the film thickness changes depending on the amount of ink printed. For example, if the CMYK values are different between adjacent pixels, unevenness can be made.

  FIG. 3 shows a relationship 56 between the total ink amount (total color material amount) [%] and the film thickness [m]. Since the total ink amounts of the first and second combinations are 167% and 155%, respectively, the film having the total ink amount of 155% by the second combination is more than the film thickness t1 of the total ink amount of 167% by the first combination. The thickness t2 is thinner.

  A hard copy HC in which a color image Ib in which an embedded image Ii having the same color reproduction as that of the original image Ia is embedded in the original image Ia is formed on the substrate 40 using the difference in film thickness depending on the total amount of ink. be able to. It is also possible to display a hard copy HC simulation image on the color monitor 28.

[Example 1]
In the first embodiment, two types of output profiles (color separation conditions: B2A-A) 52A and (B2A-B) 52B having the same color reproduction and different ink application are used, and an area having the original image Ia is used. Is assigned an output profile (B2A-A) 52A, and an output profile (B2A-B) 52B, which is a different output profile, is assigned to other areas of the original image Ia. ) The embedded image Ii is embedded in the original image Ia by switching between 52A and the output profile (B2A-B) 52B and performing image processing.

  FIG. 4 shows embedded image area information data R (x, y) as binary image data for forming the embedded image Ii. The original image data O (x, y) of the original image Ia is assigned to the pixel position of the value “0”, and the post-processing image data P (x, y) of the embedded image Ii is assigned to the pixel position of the value “1”. y) is assigned. In the example of FIG. 4, the character “A” is embedded as the embedded image Ii. However, the embedded image Ii is optional, and a desired embedded image Ii is set on the personal computer 12 using the color monitor 28 and the input device 30. Or you can choose.

  FIG. 5 shows an output profile (B2A-A) 52A selected for the original image data O (x, y) in a certain area of the original image Ia and embedded image area information that is another area of the original image Ia. According to the first embodiment, an output profile selection unit 58 that switches an output profile (B2A-B) 52B selected for original image data O (x, y) at a pixel position of data R (x, y) is provided. It is a block diagram which shows the structure of 10 A of image reproduction systems.

  In FIG. 5, the output profile selection unit 58 uses the coordinates (x, y) of the original image data O (x, y) and the coordinates (x, y) of the embedded image area information data R (x, y). In comparison, at the pixel position of the value “0” of the coordinate (x, y) of the embedded image region information data R (x, y), the output profile 52A is selected and the pixel of the original image data O (x, y). The value is converted into the device value (separation value, decomposition value) CMYK of the processed image data P (x, y), and the value “x” of the embedded image region information data R (x, y) is “ At the pixel position “1”, the output profile 52B is selected, and the pixel value of the original image data O (x, y) is converted into the device value CMYK of the processed image data P (x, y).

  Here, for example, the K value of the device value (separation value) CMYK based on the output profile (B2A-A) 52A related to the original image Ia is the device value (separation value) CMYK based on the output profile 52B related to the embedded image Ii. Is larger than the K value, the embedded image Ii is formed as an image having the same color reproduction (color) as the original image Ia and having a concave structure (dent) with respect to the original image Ia due to the difference in film thickness. The

  Note that the embedded image region information data R (x, y) can be generated from arbitrary continuous tone image data (each pixel value takes one of 0-255) by binarization processing. it can. When N (N ≧ 2) binarization processing such as quaternarization processing is generally performed in addition to the binarization processing, by preparing different N output profiles (B2A) 52, the original image Ia can be prepared. Thus, N-1 embedded images Ii having different irregularities can be embedded.

  The embedded image area information data R (x, y) does not have to be generated from the continuous tone image data. The texture (data) 60 having a pattern of bricks shown in FIG. 6A generated by calculation, or A jagged texture (data) 62 shown in FIG. 6B may be used. In the textures 60 and 62, the black line portion has the value “1” and the white portion has the value “0”. For example, a white portion is assigned to the original image Ia, and a black line portion is assigned to the embedded image Ii.

  In this case as well, using two types of output profiles 52A and 52B with the same color reproduction and different ink multiplication, the values “0” and “1” of the binary textures 60 and 62 are respectively set to By assigning and processing different output profiles (B2A-A) 52A, (B2A-B) 52B, the texture 60 itself having a pattern of bricks or the texture 62 itself having a jagged pattern are embedded in the original image Ia. Can be embedded as

  In this case, as shown in FIG. 7A, a star-shaped mask image area 74 is designated as embedded image area information data R (x, y), and as shown in FIG. 7B, this star-shaped embedded image area information An embedded image Ii with a texture 60 or the like can be embedded in the mask image area 74 specified by the data R (x, y). In this way, the embedded image Ii embedded in the original image Ia is obtained as a hard copy HC formed on the substrate 40. The embedded image Ii can be recognized by a human.

  As described above, according to the first embodiment described above, the color is determined by the total amount of ink (color material total amount) in which the ink (color material) is overlapped for each pixel, and the color image (Ia + Ii) is formed on the substrate 40. In the color image forming method (and apparatus), the color image Ib output from the color printer 16 includes an embedded image Ii in which a predetermined image is embedded in the original image Ia, and creates the color image Ib. In this case, a plurality of output profiles (B2A-A) for outputting device values (separation values) CMYK for reproducing each pixel (original image data O (x, y)) of the original image Ia with the same color of different total ink amounts. 52A, (B2A-B) 52B preparation process (means), and different output profiles (B2A-A) 52A, (B2) in the plurality of output profiles for the original image Ia and the embedded image Ii -B) assigning 52B respectively and a step (means) for color reproduction.

  In this case, the embedded image Ii can be selected from a plurality of images prepared in advance (a binary image or texture of a continuous tone image) using the input device 30 and the color monitor 28 using the personal computer 12. .

[Example 2]
In the second embodiment, the total amount of ink calculated based on the output profile (B2A) 52 is a (a ≠ 1) times (constant times) in the region specified by the embedded image region information data R (x, y). Using the total ink amount as a target ink total amount (target color material total amount), a color separation value (separated data) is calculated, and the embedded image Ii is embedded. In other words, the total ink amount (ink thickness) of the pixels of the embedded image Ii is always set to a constant a (a ≠ 1) times the total ink amount (ink thickness) of the pixels of the original image Ia. In Example 1 described above, the magnification is appropriately determined.

  According to the second embodiment, for example, when the total ink amount of the original image Ia is constant in all pixels, such as the original image Ia is one sky blue color, the difference in total ink amount between the embedded image Ii and the original image Ia ( The ink thickness difference) can be set to a (a ≠ 1) times (a times thicker or a times thinner).

  FIG. 8 shows the output profile (B2A-A) 52A selected for the original image data O (x, y) representing the original image Ia and the embedded image area information in the original image data O (x, y). The image reproduction system 10B according to the second embodiment includes a decomposition condition selection unit 66 that switches between a decomposition condition calculation unit 64 that is selected for an embedded image Ii that is specified by data R (x, y) and is created. It is a block diagram which shows a structure.

  In the image reproduction system 10B, if the pixel coordinates (x, y) of the original image data O (x, y) are not included in the embedded image area information data R (x, y), the processed image data P (X, y) is a device value (separated value) CMYK obtained by converting the device independent value Lab by the output profile (B2A-A) 52A, while the pixel coordinate (x, y) is the embedded image region. If included in the information data R (x, y), the processed image data P (x, y) is a device value (separated value) CMYK obtained by converting the device independent value Lab by the decomposition condition calculation unit 64. The

  The decomposition condition calculation unit 64 calculates a device value (separation value) CMYK for the embedded image Ii according to the procedure described below.

  The device independent value Lab for the pixel at the coordinates (x, y) of the original image data O (x, y) is converted through the output profile (B2A-A) 52A to obtain the first device value (separation value) CMYK. The first total ink amount (C + M + Y + K) is obtained from the first device value (separation value) CMYK by the total ink amount calculation unit 68, and a weighting factor a (a) that can be specified by the input device 30 for this first total ink amount. ≠ 1, a ≠ 0) is multiplied by the multiplier 70 to calculate the target ink total amount (target color material total amount), in other words, the second ink total amount as the target thickness.

  The color separation value calculation unit 72 uses the K value of the first device value (separation value) CMYK as an initial value, and when the weight coefficient a is a> 1, the second ink total amount is larger than the first ink total amount, so that the color Since the image is dark, the device value is obtained by referring to the output forward profile (A2B) 54 while gradually decreasing the K value to make the color lighter, and obtaining the device independent value Lab of the same color reproduction as the original image Ii. (Separation value) CMY is obtained.

  This procedure is repeated until the total sum (ink total amount) of device values (separation values) CMYK at this time becomes equal to the second ink total amount. However, when the K value becomes 0%, the calculation is stopped and, for example, the user uses the color monitor 28 to reduce the value of the weighting factor a (a value closer to 1). Call attention to.

  On the other hand, the color separation value calculation unit 72 uses the K value of the first device value (separation value) CMYK as an initial value, and when the weight coefficient a is a <1, the second ink total amount is smaller than the first ink total amount. Therefore, the device independent value Lab having the same color reproduction as that of the original image Ii is obtained by referring to the output forward profile (A2B) 54 while gradually increasing the K value in order to darken the color because the color is lighter. The device value (separation value) CMYK is obtained. This procedure is repeated until the total sum (ink total amount) of device values (separation values) CMYK at this time becomes equal to the second ink total amount. However, when the K value reaches 100%, the calculation is stopped, and the user is alerted using the color monitor 28, for example.

  According to the above procedure, the total ink amount of the embedded image Ii based on the processed image data P (x, y) can be observed for each small region of the original image Ia with respect to the total ink amount of the original image Ia (microscopically observed). In other words, the total ink amount difference (thickness difference) between the embedded image Ii and the original image Ia is approximately a times constant.

  FIG. 9 is a flowchart explaining the above-described procedure of the decomposition condition calculation unit 64 more easily in consideration of specific numerical examples.

  In step S1, the device independent value Lab obtained from the input profile (A2B) 50 is converted into a first device value (separated value) CMYK by the output profile (B2A-A) 52A. Here, for example, assuming that the first device value (separation value) CMYK is C = 60, M = 60, Y = 50, and K = 30, the ink total amount calculation unit 68 performs the first operation in step S2. The total amount of ink is calculated as C + M + Y + K = 200.

  Next, in step S3, when the weighting coefficient a is set to a = 1.05, the second ink total amount that is the target ink total amount is determined to be 200 × 1.05 = 210, and the color separation value calculation unit 72 performs the initial of repeated calculation. A condition is set.

  The initial conditions are the second ink total amount = 210, the initial value K of K = 30, and the device independent value Lab (input value in step S1).

  Next, in step S4, the K value is slightly decreased, for example, by a minute amount ΔK = 1% (K ← K−ΔK). In this step S4, when the weighting coefficient a is a <1, the value is increased by a minute amount ΔK (K ← K + ΔK).

  In step S5, a device value (separation value) CMY satisfying the device independent value Lab, K = 29 is obtained with reference to the output forward profile (A2B) 54.

  Next, in step S6, it is determined whether the total ink amount C + M + Y + K based on the obtained device value (separation value) CMYK is equal to or greater than the second ink total amount (target ink total amount) = 210 (C + M + Y + K ≧ 210). If the device value (separation value) CMYK is determined, and if it is a small value (if it is negative), the K value is further decreased by a small amount to perform the same operation. In step S8, the reduction amount ΔK is increased (ΔK ← ΔK + 1%). Thereby, the K value in the next step S4 is changed from the value 29 to the value 28.

  By repeating the above procedure, a device value (separation value) CMYK of the same color reproduction close to the second ink total amount (target ink total amount) can be obtained.

  According to the second embodiment, in the color image forming method in which the color is determined based on the total amount of ink (color material total amount) in which the color material is superimposed on each pixel and the color image is formed on the substrate 40, the color image Ib is: K includes an embedded image Ii in which a predetermined image is embedded in the original image Ia, and is a device-dependent value corresponding to the device independent value Lab of each pixel of the original image Ia when the color image Ib is created. An output profile (B2A-A) 52A that outputs device values (separated values) CMYK including values and an output forward profile (A2B) 54 that converts device values (separated values) CMYK to device independent values Lab are prepared. When the original image Ia is reproduced on the base material 40 by the output profile (B2A-A) 52A, the original image is output using the output profile (B2A-A) 52A. After calculating a device value (separation value) CMYK including the K value of the color image (embedded image) Ib existing at the pixel position of Ia, it is the sum of the device values (separation value) CMYK including the K value. A process (means) for calculating a target ink total amount (target color material total amount) obtained by multiplying the total ink amount (color material total amount) by a weighting factor a, and when the weighting factor a is a> 1, while gradually decreasing the K value, When the weighting factor a is a <1, the output forward profile (A2B) 54 is referred to while gradually increasing the K value, and a device independent value equal to or closest to the device independent value Lab of each pixel of the original image Ia is obtained. Output device values (separation values) CMYK.

  Even in this case, since the total amount of ink (total amount of color material) differs between the original image Ia and the embedded image Ii, a human can recognize the embedded image Ii.

[Example 3]
In the third embodiment, a grayscale image (multi-valued image) 76 as shown in FIG. 10A is designated as an embedded image Ii, and embedded image data H (x, y) = v ( v is a pixel value, for example, any one of 1-255.) is subjected to predetermined image processing. By this image processing, as shown in FIG. 10C, a color image Ib in which the grayscale image 76 shown in FIG. 10A is embedded as the embedded image Ii in the original image Ia shown in FIG. 10B is created. Then, the color printer 16 outputs a hard copy HC in which the color image Ib based on the processed image P (x, y) is formed on the substrate 40.

  In the third embodiment, when the embedded image Ii is the grayscale image 76, the weighting coefficient a is changed according to the pixel value v of the grayscale image 76.

  FIG. 11 shows a decomposition condition for switching between the output profile (B2A-A) 52A selected for the original image Ia and the decomposition condition calculation unit 164 selected for the embedded image Ii corresponding to the grayscale image 76. It is a block diagram which shows the structure of 10 C of image reproduction systems which provided the selection part 166.

  In FIG. 11, the embedded image area information data R (x, y) is “1” in the area where the embedded image data H (x, y) has the gray scale image 76 (v ≠ 0), and the gray scale image. In a region where 76 does not exist, a value of “0” is taken.

  The image reproduction system 10C in the example of FIG. 11 changes the weighting coefficient a depending on the pixel value v of the embedded image data H (x, y) as compared with the image reproduction system 10B in the example of FIG. The total ink amount (target color material total amount) of the embedded image Ii is changed depending on the pixel value v.

  In the third embodiment, as shown in the characteristics 80 and 82 of FIG. 12, the weight coefficient a is a linear function 1 + h × v (intercept is 1) with h (h ≠ 0) as a constant, and the total ink amount is (1 + h). Xv) The device value (separation value) CMYK is calculated using the multiplied total amount of ink as the target total amount of ink. The function for changing the total ink amount depending on the pixel value v is not limited to a linear function, and an arbitrary monotonically increasing function or a monotonically decreasing function can be selected.

  In the image reproduction system 10C in the example of FIG. 11, the processing by the separation value calculation unit 72 is performed in the same manner as in the second embodiment. In this image reproduction system 10C, the amplitude of the unevenness of the embedded image Ii can be controlled by the constant h.

  That is, in the embedded image area information data R (x, y), the color reproduction is the same as that of the original image Ia, but the total ink amount of the embedded image Ii can be monotonously increased or decreased monotonously according to the pixel value v. it can.

  As described above, according to the first embodiment, the second embodiment, and the third embodiment described above, a color image including an embedded image Ii in which a predetermined image is embedded in the original image Ia using four or more color materials. In the image processing method applied to the image forming apparatus such as the color printer 16 that forms the image on the substrate 40, the same color as the color to be reproduced for the pixels of the original image Ia is reproduced, and the total amount of ink (color A plurality of device values (separation values) CMYK that are combinations of a plurality of color materials having different material total amounts) are acquired, and the pixel values of the pixels of the embedded image Ii corresponding to the pixel positions of the original image Ia are A combination of color materials for forming the embedded image Ii is obtained from a plurality of device values (separation values) CMYK which are combinations of a plurality of color materials.

  Therefore, a color image Ib in which the embedded image Ii is embedded in the original image Ia created by a relatively easy method can be obtained by an image forming apparatus such as the color printer 16 that performs color reproduction with four or more colors. . Further, an embedded image Ii that can be recognized by a human can be embedded in the original image Ia by a relatively easy method.

  In this case, the embedded image Ii is an N (N ≧ 2) value image, and the color device value (separation value) CMYK (combination of color materials) to be reproduced for the pixels of the original image Ia is used as a reference. The first ink total amount (color material total amount) for the combination of the obtained device value (separation value) CMYK is calculated from the output profile (B2A-A) 52A, which is the color conversion characteristic, and the first ink total amount (color The target ink total amount (target color material total amount) is calculated by multiplying the total material amount) by the ratio given by the pixel value function (1 + h × v) of the embedded image Ii. Find similar colorant combinations.

  In this case, the function (1 + h × v) of the pixel value of the embedded image Ii is a constant multiple (weighting factor a) when the embedded image Ii is a binary image, and is a grayscale image of three or more values. Is a linear function (1 + h × v) times the pixel value with the intercept value “1”.

  According to the first to third embodiments described above, the color image Ib in which the embedded image Ii having the same color reproduction as the original image Ia is embedded by the image forming apparatus such as the color printer 16 that performs color reproduction with four or more colors is dedicated. This device can be obtained with a simple configuration that does not require this device. In other words, a post process and a post process are unnecessary. High-resolution textures 60 and 62 can be embedded by controlling processing for each pixel.

  Each of the above-described inventions is not easily counterfeited or tampered with, and is suitable for application to valuable printed matter such as banknotes, securities, passports, identification cards, cards, stamps, certificates, admission tickets and the like.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the contents described in this specification.

1 is a configuration diagram of an image reproduction system to which a color image forming method, a color image forming apparatus, an image processing method, and an image processing apparatus according to an embodiment of the present invention are applied. It is the functional block diagram which showed the data flow in the normal image processing of the image reproduction system when not embedding an embedded image. FIG. 6 is an explanatory diagram illustrating a relationship between a total ink amount (total color material amount) [%] and a film thickness [m]. It is explanatory drawing which shows the example of the embedding image area | region information data as binary image data for forming an embedding image. 1 is a block diagram illustrating a configuration of an image reproduction system according to a first embodiment in which an output profile selection unit that switches output profiles is provided. FIG. 6A is an explanatory diagram of a brick texture, and FIG. 6B is an explanatory diagram of a jagged texture. FIG. 7A is an explanatory diagram of the mask image area of the embedded image, and FIG. 7B is an explanatory diagram of the processed image. FIG. 10 is a block diagram illustrating a configuration of an image reproduction system according to a second embodiment. 10 is a flowchart provided for explaining processing in the second embodiment. 10A is an explanatory diagram of a grayscale image, FIG. 10B is an explanatory diagram of an original image, and FIG. 10C is an explanatory diagram of a processed image. FIG. 10 is a block diagram illustrating a configuration of an image reproduction system according to a third embodiment. FIG. 10 is an explanatory diagram of a linear function according to the third embodiment.

Explanation of symbols

10, 10A, 10B, 10C ... Image reproduction system 12 ... Personal computer 14 ... Color scanner 16 ... Color printer 22 ... CPU
DESCRIPTION OF SYMBOLS 40 ... Base material 50 ... Input profile 52, 52A, 52B ... Output profile 54 ... Output forward direction profile 60, 62 ... Texture 64, 164 ... Decomposition condition calculation part 66, 166 ... Decomposition condition selection part 72 ... Separation value calculation part 76 ... Grayscale image

Claims (9)

In a color image that is formed on a base material and the color is determined by the total amount of the color material overlaid on each pixel,
The color image includes an embedded image in which a predetermined image is embedded in the original image, and the embedded image has the same color reproduction as the original image at each pixel position of the embedded image, and A color image in which a predetermined image is embedded in an original image, which is formed with a total color material amount different from the total color material amount of the original image. The color image according to claim 1,
The embedded image is an N (N ≧ 2) value image;
A color image in which a predetermined image is embedded in an original image, wherein the embedded image is formed by N-1 different total color material amounts. In a color image forming method in which a color is determined by a total amount of color material obtained by overlapping color materials for each pixel and a color image is formed on a base material,
The color image includes an embedded image in which a predetermined image is embedded in an original image, and when creating the color image,
A step of preparing a plurality of output profiles for outputting separation values for reproducing each pixel of the original image with the same color of different color material total amount;
A color image forming method comprising: assigning different output profiles of the plurality of output profiles to the original image and the embedded image, respectively, and reproducing colors. The color image forming method according to claim 3.
A color image forming method, comprising: selecting the embedded image from a plurality of images prepared in advance. In an image processing method applied to an image forming apparatus for forming a color image including an embedded image in which a predetermined image is embedded in an original image by using four or more color materials,
Reproducing the same color as the color to be reproduced for the pixels of the original image, and obtaining a combination of a plurality of color materials having different total color material amounts,
In accordance with the pixel value of the pixel of the embedded image corresponding to the pixel position of the original image, a combination of color materials for forming the embedded image is obtained from the combination of the plurality of color materials.
An image processing method. The image processing method according to claim 5.
The embedded image is an N (N ≧ 2) value image,
Obtaining a combination of color materials to be reproduced for the pixels of the original image from the standard color conversion characteristics,
Calculate the total color material amount for the obtained combination of color materials,
The target color material total amount is calculated by multiplying the color material total amount by a ratio given as a function of the pixel value of the embedded image,
An image processing method comprising: obtaining a color material combination closest to the target total color material amount. The image processing method according to claim 6.
The function of the pixel value of the embedded image is a constant multiple when the embedded image is a binary image, and a pixel value with an intercept value “1” when the embedded image is a grayscale image of three or more values. An image processing method characterized by having a multiple of a linear function. In a color image forming apparatus for forming a color image on a base material by determining a color based on a total amount of color material obtained by overlapping color materials for each pixel,
The color image includes an embedded image in which a predetermined image is embedded in an original image,
Means for preparing a plurality of output profiles for outputting color separation values for reproducing each pixel of the original image with the same color of different color material total amount;
A color image forming apparatus comprising: means for assigning different output profiles of the plurality of output profiles to the original image and the embedded image, respectively, and reproducing colors. In an image processing apparatus for an image forming apparatus that uses a color material of four or more colors to form a color image including an embedded image in which a predetermined image is embedded in an original image on a base material,
Means for reproducing the same color as the color to be reproduced for the pixels of the original image and obtaining a combination of a plurality of color materials having different total color material amounts;
Means for obtaining a combination of color materials for forming the embedded image from a combination of the plurality of color materials according to a pixel value of a pixel of the embedded image corresponding to a pixel position of the original image;
An image processing apparatus comprising:

Images